San Francisco 49ers Kyle Williams runs 56 yards for a touchdown against the St. Louis Rams,in the fourth quarter, Sunday Dec. 4, 2011, at Candlestick Park in San Francisco, Calif.

Photo: Lacy Atkins, The Chronicle

San Francisco 49ers Kyle Williams runs 56 yards for a touchdown...

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San Francisco 49ers head coach Jim Harbaugh check on Patrick Willis after he tackled St. Louis Rams Brit Miller in the first quarter, Sunday Dec. 4, 2011, 26-0, at Candlestick Park in San Francisco, Calif. Willis was hurt in the play with a hamstring inquiry and this out the rest of the game.

San Francisco 49ers quarterback Alex Smith gets a hand off in the second half against the St. Louis Rams, Sunday Dec. 4, 2011, at Candlestick Park in San Francisco, Calif.

Photo: Lacy Atkins, The Chronicle

San Francisco 49ers quarterback Alex Smith gets a hand off in the...

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San Francisco 49ers Frank Gore runs to make a first down against the St. Louis Rams, Sunday Dec. 4, 2011, at Candlestick Park in San Francisco, Calif. Gore broke the team rushing recorded.

Photo: Lacy Atkins, The Chronicle

San Francisco 49ers Frank Gore runs to make a first down against...

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San Francisco 49ers Kendall Hunter, left congratulates Michael Crabtree along with Ted Ginn Jr. after making a touchdown in the third quarter against the St. Louis Rams, Sunday Dec. 4, 2011, at Candlestick Park in San Francisco, Calif.

Photo: Lacy Atkins, The Chronicle

San Francisco 49ers Kendall Hunter, left congratulates Michael...

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San Francisco 49ers fans cheer as as they defeat the St. Louis Rams, 26-0, Sunday Dec. 4, 2011, at Candlestick Park in San Francisco, Calif.

Photo: Lacy Atkins, The Chronicle

San Francisco 49ers fans cheer as as they defeat the St. Louis...

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San Francisco 49ers Kyle Williams runs for a touchdown against the St. Louis Rams in the second half, Sunday Dec. 4, 2011, at Candlestick Park in San Francisco, Calif.

Photo: Lacy Atkins, The Chronicle

San Francisco 49ers Kyle Williams runs for a touchdown against the...

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San Francisco 49ers head coach Jim Harbaugh walks off the field after the 49ers defeated the Rams 26-0, Sunday Dec. 4, 2011, at Candlestick Park in San Francisco, Calif.

Photo: Lacy Atkins, The Chronicle

San Francisco 49ers head coach Jim Harbaugh walks off the field...

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San Francisco 49ers quarterback Alex Smith is sacked by St. Louis Rams Robert Quinn in the second half against, Sunday Dec. 4, 2011, at Candlestick Park in San Francisco, Calif.

Photo: Lacy Atkins, The Chronicle

San Francisco 49ers quarterback Alex Smith is sacked by St. Louis...

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St. Louis Rams quarterback Donnie Jones is sacked by San Francisco 49ers Aldon Smith in the second half, Sunday Dec. 4, 2011, at Candlestick Park in San Francisco, Calif.

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St. Louis Rams quarterback Donnie Jones is sacked by San Francisco...

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San Francisco 49ers Patrick Willis tackles St. Louis Rams Brit Miller in the first quarter, Sunday Dec. 4, 2011, 26-0, at Candlestick Park in San Francisco, Calif. Willis was hurt in the play with a hamstring inquiry and this out the rest of the game.

Photo: Lacy Atkins, The Chronicle

San Francisco 49ers Patrick Willis tackles St. Louis Rams Brit...

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San Francisco 49ers Michael Crabtree celebrates with Ted Ginn Jr. as they defeat the St. Louis Rams, Sunday Dec. 4, 2011, 26-0, at Candlestick Park in San Francisco, Calif.

Photo: Lacy Atkins, The Chronicle

San Francisco 49ers Michael Crabtree celebrates with Ted Ginn Jr....

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San Francisco 49ers Kyle Williams is congratulates by team and head coach Jim Harbaugh tries the break loss of St. Louis Rams Chris Chamberlain in the second half, Sunday Dec. 4, 2011, at Candlestick Park in San Francisco, Calif.

Photo: Lacy Atkins, The Chronicle

San Francisco 49ers Kyle Williams is congratulates by team and...

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San Francisco 49ers Kyle Williams tries the break loss of St. Louis Rams Chris Chamberlain in the second half, Sunday Dec. 4, 2011, at Candlestick Park in San Francisco, Calif.

Photo: Lacy Atkins, The Chronicle

San Francisco 49ers Kyle Williams tries the break loss of St....

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San Francisco 49ers Frank Gore runs to make a first down against the St. Louis Rams, Sunday Dec. 4, 2011, at Candlestick Park in San Francisco, Calif. Gore broke the team rushing recorded.

With Braylon Edwards inactive because of knee and shoulder injuries Sunday, Kyle Williams received more playing time in a 26-0 win over the Rams.

It's safe to say the 49ers' second-year wideout made the most of his opportunity.

After a sputtering performance by San Francisco's offense in the first half, Williams helped highlight a second-half resurgence - running 25 yards on a reverse to set up a David Akers field goal and adding a 56-yard touchdown catch from Alex Smith in the fourth quarter in which he outran the secondary for the final 48 yards.

"They told us Braylon was going to going to be sitting down," Williams said. "So, next man up."

Williams (2 catches, 66 yards) continued to make a case to earn more playing time, regardless of Edwards' health. In the past three games, Williams has caught seven of the eight passes thrown in his direction. This season, he has 11 catches for 162 yards and three touchdowns, matching the touchdown total of the rest of San Francisco's wide-receiving corps.

Williams, who has remained healthy this season after an injury-marred, one-catch rookie season, is known for his speed and quickness, something the Niners lack on the outside. But he also flashed surprising physicality Sunday.

Near the end of his 25-yard reverse in the third quarter, the 5-foot-10, 186-pounder threw Rams' 204-pound safety Quintin Mikell down with a violent stiff-arm.

Williams' lone misstep might have come after the game. The son of White Sox general manager Kenny Williams, he was wearing a Chicago cap as he spoke with reporters.

Asked why he wasn't wearing a 49ers division-title souvenir cap, he reached back into his locker and swapped hats.